Viral conjunctivitis is most often caused by a highly contagious adenovirus infection. The inflammation in this image is mild. The subconjunctival hemorrhage shown here is rare in adenoviral conjunctivitis.

Image courtesy of the Ophthalmic Clinic of the Health Center of the University of Erlangen-Nürnberg, via the Online Journal of Ophthalmology (www.onjoph.com).